The invention relates to a spinning, twisting, or spooling machine, especially to a draw-twisting frame for the processing of synthetic endless threads, in which the thread is stretched or drawn between a feed roller which is preferably common to several processing stations, and draw rollers, or godets, associated with each processing station and is subsequently wound up on spools.
In draw-twisting frames of customary construction, the draw rollers, also called godets or galettes, which transport the threads, are driven by a common shaft via directly meshing gears. The drive shaft is connected, through directly meshing gear trains, with the shaft or shafts of the feed roller or rollers which deliver the thread to the draw rollers or godets. The gear ratio between the feed rollers and the draw rollers is so chosen that the desired stretching (drawing) of the threads is achieved.
After the stretching operation, the threads are wound up on spools which can be fastened on spindles. The threads are wound up with the aid of a ring and traveler while being twisted. In the usual case, the spindles are driven by positively engaging belts from a common driving shaft. Powering by means of a tangential belt which is guided alongside the whorls of the spindles is also known. In other cases, the threads are wound up on spools which are powered by positive contact with a friction roller. In all these cases, the threads are wound up without rotation (draw-spooling frame). However, these drive methods limit the rotational speed which can be attained by the working elements, especially by the draw rollers and the spindles, and therefore, also limit the operational speed of the machine and its rate of production. At the draw rollers, the gear transmissions cause problems related to lubrication, wear and tear, and noise, making an increase of the rotational speed beyond a certain limit uneconomical or even impossible. The noise generated by the belt drive of the spindles also leads to excessive annoyance when the spindle rpm is further increased and, in addition, a positive belt drive is unsatisfactory for transmitting the required start-up energy, especially for spools whose thread packages have already acquired some weight.
For this reason, it has already been proposed (U.S. Pat. No. 3,009,308) to provide individual drive means for the feed roller, the draw roller, and the spindle of each processing station in the form of an individual motor, whereby the drive motors of the feed roller and of the draw roller are synchronous motors, whereas the drive motor of the spindle is an asynchronous motor. The power for these motors is supplied by frequency generators.
It has been shown that, for example, a static frequency generator or frequency converter which could handle the switch-on current transient would have to be approximately ten times as large as necessary for normal operation, i.e., for supplying the energy required by a running machine. Such an over dimensioning of the frequency generator is not economical.